1. Field of the Invention
The present invention relates to an electrostatic breakdown prevention apparatus for an electronic apparatus, and more particularly to an electrostatic breakdown apparatus suitable for use with an electronic apparatus which is used frequently outdoors or at a like place where the electronic apparatus is likely to be influenced by static electricity.
2. Description of the Related Art
An electronic apparatus, particularly a portable electronic apparatus that is connected to an external apparatus through a connector and bidirectionally transfers data at a high speed to or from the external apparatus using the same signal line is conventionally known.
A connector of a portable apparatus to an external apparatus includes, at signal inputting and outputting portions thereof, an electric circuit for smoothing a high voltage applied momentarily thereto to prevent a breakdown of an internal electric circuit by static electricity as a countermeasure to allow the portable apparatus to be used frequently outdoors or at a like place.
However, increase of the speed of data transfer of such portable apparatus has been and is proceeding in recent years, and such a smoothing circuit as described above makes an obstacle to high speed data transfer. Therefore, it is demanded to realize both of prevention of static electricity and high speed data transfer.
Also it is demanded to reduce the number of connection lines of a connector involved in miniaturization of a portable apparatus and to achieve bidirectional data transfer on the same line.
In order to satisfy such demands as described above, a connector has been proposed in Japanese Patent Laid-Open No. 062076/1985 wherein, when the connector is not in a non-connecting state, a connector terminal unit structure itself is grounded in order to prevent an electrostatic breakdown. However, when the connector is placed into a connecting state, the connector terminal unit structure is brought into a non-grounded state.
The apparatus disclosed in the prior art document mentioned above cannot be configured so as to prevent an electrostatic breakdown of a pair of apparatus connected to the opposite sides of the connector where one of the two apparatus transfers a signal bidirectionally using the same signal line of the connector.
Further, for portable apparatus, the shape of a connector unit which can be used is sometimes prescribed in specifications of an interface to be used. In this instance, the apparatus disclosed in the prior art cannot be applied.